Need help to get rid of my ex's threat

I met this guy when I was 18 (2008) , he introduced him self as a 24year old and a single man . Our relationship was going stronger and we had physical relationship as well . Since am from a strong family , he suggested that we get married and keep it as a secret , I wasn't ready , so he suggested that I add his name in my passport . So that nobody LL know and also legally nobody can seperate us .with an affidavit he helped endorse his name in my passport . 1 ,1/2 year of relationship and his name in my passport , I found out that he was already married and has a kid who is almost 2 years old . I couldn't do much but to cry and eventually broke off the relationship . Am married , in the mean time(2012) this ex created a fake profile in my name and photograph , when confronted he said he was spying his wife . I didn't want to put my head into this , so I let him but asked him a favor to help me take his name off passport . He refused and called me names . After two years , now he started sending me messages apologising , then when I asked him to stop, he threaten about my photos and videos , and also when husband asked him to stop contacting me , he is threatening us . Not only o want his name removed from my passport but I want him to stop threatening or harassing me. Am based out of Chennai. Because of him my parents don't even talk to me . So if one of you could suggest me pr help with legal guidance to sue him . I would be grateful . I have been married for 4 1/2 years and I have a baby .